Lithium-ion Battery with Segmented Electrolyte pH Control
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Solution Overview
Problem
Current lithium-ion secondary batteries with aqueous electrolytic solutions have insufficient charge and discharge characteristics, necessitating improvements in their performance.
Innovation Solution
The lithium-ion secondary battery design incorporates a titanium-containing compound as the negative electrode active material, with an electrolytic solution pH of 11 or higher, and a partition to separate positive and negative electrode spaces, allowing lithium ions to pass through while maintaining distinct pH levels in each electrolyte solution, enhancing charge and discharge efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If an aqueous electrolytic solution is used in a lithium-ion secondary battery, then the battery size can be reduced and energy density increased, but the charge and discharge characteristics become insufficient
Solution Approach 1:
The patent applies local quality by creating distinct pH environments in different regions of the battery. The negative electrode space maintains high pH (≥11) to prevent electrolysis and improve charge-discharge characteristics, while the positive electrode space maintains low pH (<11) to suppress oxygen evolution. This spatial differentiation of chemical properties resolves the contradiction between using aqueous electrolyte for compactness and maintaining good charge-discharge performance.
Solution Approach 2:
The patent segments the electrolytic solution into two separate compartments with different pH characteristics. By dividing the battery into positive and negative electrode spaces separated by a partition, each space can be optimized independently - the negative electrode space for high pH operation and the positive electrode space for low pH operation - thereby achieving both reduced battery size and improved charge-discharge characteristics.
2Productivity
If the electrolytic solution pH is increased to 11 or higher to improve charge and discharge efficiency, then electrolysis of the aqueous electrolytic solution occurs
Solution Approach 1:
The patent segments the electrolytic solution into two separate compartments. The negative electrode space contains high pH electrolyte (pH ≥11) that enables efficient charge-discharge without electrolysis, while the positive electrode space contains low pH electrolyte (pH <11) that suppresses oxygen evolution. The partition prevents mixing, allowing each compartment to operate in its optimal pH range without generating harmful electrolysis effects.
Solution Approach 2:
The patent creates localized high pH conditions specifically at the negative electrode where they are needed for efficient lithium ion insertion/extraction, while maintaining low pH at the positive electrode to prevent oxygen evolution. This localized control of pH properties allows high charge-discharge efficiency without the harmful electrolysis that would occur if the entire electrolyte were at high pH.
3Productivity
If a partition is introduced to separate positive and negative electrode spaces with different pH levels, then charge and discharge characteristics improve, but device complexity increases
Solution Approach 1:
The patent introduces a partition as an intermediary component that separates the positive and negative electrode spaces. This partition maintains the pH gradient between compartments while still allowing lithium ion transport, thus improving charge-discharge characteristics without completely isolating the two electrode systems. The partition acts as a mediator that enables the beneficial pH differentiation while maintaining battery functionality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration achieves superior charge and discharge characteristics by preventing degradation, ensuring stable operation, and maintaining high discharge capacity even with repeated charging and discharging.
Implementation Method 1
The partition is disposed between a positive electrode space and a negative electrode space, and allows a lithium ion to pass therethrough
Implementation Method 2
The negative electrode includes a negative electrode active material which the lithium ion is to be inserted into and extracted from
Implementation Method 3
The positive electrode is an electrode which a lithium ion is to be inserted into and extracted from
Data Source
AI summary
A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode is an electrode which a lithium ion is to be inserted into and extracted from. The negative electrode includes a negative electrode active material which the lithium ion is to be inserted into and extracted from. The electrolytic solution includes an aqueous solvent. The negative electrode active material includes a titanium-containing compound. The electrolytic solution has a pH that is higher than or equal to 11. Based on a surface analysis of the negative electrode by X-ray photoelectron spectroscopy, a proportion of a sum of respective detectable amounts of lithium, titanium, tin, zirconium, bismuth, and indium to a sum of respective detectable amounts of all of metal elements is greater than or equal to 99 atom %.